Molybdenum compounds in lubricants



United States atent 3,494,866 MOLYBDENUM COMPOUNDS IN LUBRICANTS Eugene V. Rowan, Rowayton, and Homer H. Farmer,

Westport, Conn., assignors to R. T. Vanderbilt Company, Inc., New York, N.Y., a corporation of New York No Drawing. Original application Oct. 28, 1965, Ser. No. 505,451, now Patent No. 3,400,140, dated Sept. 3, 1968. Divided and this application Apr. 12, 1968, Ser. No. 736,881

Int. Cl. C10m 3/48, 5/28 US. 'Cl. 25232.7 9 Claims ABSTRACT OF THE DISCLOSURE The specification relates to a composition containing (A) a lubricating oil or grease and (B) certain sulforized oxymolybdenum organophosphorodithioate compounds. It also relates to a process for preparing this composition.

wherein R is an alkyl, cycloalkyl, aryl or alkaryl group having 1 to 30 carbon atoms. If R is an alkyl group, the preferred number of carbon atoms is 1 to 20 and the especially preferred number of carbon atoms is 3 to 8. If R is an aryl group, the preferred number of carbon atoms is 6 to 26, i.e., .phenyl and alkyl-substituted phenyl groups wherein the alkyl su-bstituent contains 1 to 20 carbon atoms, such as 4 to 9 carbon atoms. The compounds, however, have only one phosphorodithioate radical per molybdenum atom.

In the present invention, the compounds may be prepared by dissolving molybdic oxide in a solution of alkali metal hydroxide, magnesuim hydroxide, beryllium hydroxide or ammonium hydroxide and by the incorporating subsequently an approximately equivalent amount, based on hydroxide, of a strong mineral acid, such as sulfuric acid. An organophosphorodithioic acid reactant may be separately prepared by treating a monohydric alcohol or phenol with phosphorus pentasulfide in the mole ratio of 4:1. The phosphorodithioic acid reactant is then added to the aforementioned molybdate solution with subsequent finishing operations to form a sulfurized oxymolybdenum organophosphorodithioate.

It is important herein to heat the mixture of phosphorodithioic acid and molybdate solution at the reflux temperature, e.g., from about 85 to 100 C. The reaction time is generally 1 to 5 hours.

It is also important herein to use 2 mole of phosphorodithioic acid reactant for each mol of molybdate reactant to obtain a maximum yield of the product of this invention having one phosphorodithioate radical per molybdenum atom. No catalyst is required for the reaction. Water is a suitable solvent but other inert solvents may be present, such as a low viscosity aromatic base oil.

The reaction product, i.e., sulfurized oxymolybdenum organophosphorodithioate, may be solid or liquid depending on the organic radical in the phosphorodithioic acid reactant. If the molybdenum-containing product is a solid, it is recovered by filtration If the molybdenumcontaining product is a liquid, it is recovered by filtering out any solid by-products and by distilling to remove the solvent.

A compound of the invention may be employed as a lubricant, per se. This includes using it as an antiwear agent or as an extreme pressure agent. A compound of the invention also may be employed as an additive in any lubricating oil or grease. As an additive, the compound is generally used in a minor amount, e.g., 0.2% to 20%, preferably 0.2% to 10%. Therefore, a known pertoleumbased lubricant, such as turbine oil, other light oils, SAE gear oil and other heavy oils, or a known synthetic lubricant, such as esters, polyethers and silicones, may have therein a molybdenum-containing compound within the scope of the present invention. Besides the aforementioned molybdenum compound, the lubricating oil or grease may contain conventional additives, such as thickening agents for the production of lubricating greases (e.g., clay, other pigments, alkali metal soaps, alkaline earth metal soaps or other soaps), corrosion inhibitors, antioxidants, antirust agents, viscosity improvers, pour point depressants, detergents, other extreme pressure agents, other antiwear agents and the like.

Thus, in accordance with this invention, new sulfurized oxymolybdenum organophosphorodithioate compounds have been formed with one phosphorodithioate radical for each molybdenum atom. These compounds have antiwear and extreme pressure properties and act as antioxidants when formulated in lubricating oils and greases. Furthermore, the compounds of the invention have the same properties when used per se on rubbing metal surfaces.

The following examples are submitted to illustrate but not to limit this invention. Unless otherwise indicated, all parts and percentages in the specification and claims are based upon weight.

Example I Sulfurized oxymolybdenum di-isopropylphosphorodithioate was prepared by placing pure molybdic oxide, 72 grams (0.5 mole), and 300 ml. of water in a 1-liter, 3- necked flask equipped with stirrer, thermometer and reflux condenser. Sodium hydroxide, 35 grams of 50% solution (0.44 mole), was then added and the mixture was heated to effect solution. Sulfuric acid, 21.7 grams of 96% acid (0.21 mole), was added subsequently and the mixture was cooled below 50 C. This was followed by the addition of di-isopropylphosphorodithioic acid, 268 grams of 80% active material in a low viscosity aromatic base oil (1.0 mole). The resulting mixture was heated at reflux (SS- C.) for two hours, cooled and filtered. The filter cake was washed successively with water, methanol and hexane to yield 177.0 grams of a yellow solid. When recrystallized from hexane, the sulfurized oxymolybdenum di-isopropylphosphorodithioate melted at 140l41 C. and had the followihg analysis:

Calc. for C H P S O Mo C, H, S, 26.2%. Found: C, 20.52%; H, 3.94%; S, 25.52%.

The infrared spectrum of sulfurized oxymolybdenum di-isopropylphosphorodithioate showed the following absorption maxima:

Strength: Microns Strong 3.45 Moderate 6.85

Moderate 7.29

Moderate 8.50

Weak 9.10

Very strong 10.27 Moderate 11.20

Moderate to strong 13.07 Moderate 13.40

Weak to moderate 14.00

Example II Sulfurized oxymolybdenum di-isobutylphosphorodithioate was prepared from pure molybdic oxide, 36 grams (0.25 mole), in 100 ml. water dissolved in 17.5 grams of 50% sodium hydroxide solution (0.22 mole) as described for Example I. The mixture was treated with 10.52 grams of 96% sulfuric acid (0.11 mole), and the solution was cooled below 50 C. before adding 181.0 grams (0.50 mole) of di-isobutylphosphorodithioic acid. The mixture therefrom was heated for two hours at 95- 100C., cooled and poured into a separatory funnel. The oily layer was separated, washed with water and allowed to stand overnight. The solidifiied product was slurried in methanol and filtered, yielding a yellow solid. After recrystallization from hexane, 50 grams of purified sulfurized exymolybdenum di isobutylphosphoridithioate were obtained which melted at 9596 and which had an analysis as follows:

Calc. for C16H36P2S MO2i C, H, P, 8.04%; S, 24.96%; Mo, 24.90. Found: C, 25.19%; H, 4.65%; P, 8.00%; S, 24.87%; Mo, 24.26%.

The infrared spectrum of sulfurized oxymolybdenum di-isobutylphosphoroditioate showed the following absorption maxima:

Strength: Microns Strong 3.45 Moderate to strong 6.85 Moderate 7.20 Triplet:

Strong 9.80 Very strong 10.05 Strong 10.27 Moderate 11.88

Example III By following the procedure of Example I, sulfurized oxymolybdenum di (2 ethylhexyl)phosphorodithioate was formed from a mixture of pure molybdic oxide, 50 grams (0.35 mole), and 75 ml. of water which was treated with 24.2 of 50% sodium hydroxide solution (0.30 mole) with subsequent heating to effect solution. Sulfuric acid, 14.6 grams of 96% acid (0.14 mole), Was added and the solution Was cooled below 50 C. After adding 245 grams (0.69 mole) of di-(Z-ethylhexyl)phosphorodithioic acid, the resulting mixture was heated for five hours at 95100 C. and was then poured into a separatory funnel. The oily layer was separated, washed with water and dissolved in hexane. The hexane solution was then washed with water and the solvent was evaporated to yield 265 grams of brown, liquid sulfurized oxymolybdenum di-(2- ethylhexyl)phosphorodithioate which was tested without further purification. The infrared spectrum of the sulfurized oxymolybdenum di-(2-ethylhexyl)phosphorodithioate showed absorption maxima as follows:

Absorption: Microns Strong 3.45 Moderate to strong 6.85 Moderate 7.25 Weak to moderate 8.7 Very strong 10.10 Moderate 10.55 Weak 12.30 Weak 13.9

Example IV The preparation of sulfurized oxymolybdenum di-(ptertiary butylphenyl)phosphorodithioate was accomplished by placing pure molybdic oxide, 72 grams (0.5 mole), and 500 ml. water in a 2-liter, 3-necked flask equipped with stirrer, thermometer and condenser. Then 35 grams of 50% sodium hydroxide solution (0.44 mole) were added and the mixture therefrom was heated to effect solution. Sulfuric acid, 21.7 grams of 96% acid (0.21 mole), was added and the resulting solution was cooled below 50 C. before adding 372 grams (1.0 mole) of di-(p-tertiary-butylphenyl)phosphorodithioic acid. This mixture was refluxed for two hours, cooled and filtered to yield 70 grams of a brown solid. When recrystallized several times from toluene, a tan product, sulfurized oxymolybdenum dip-tertiary-butylphenyl phosphorodithioate, was obtained. This product melted at 225227 C. and had the following analysis:

Calc. for C40H32P2S6M5MO2: C, H, S, 17.90%; mol. wt., 1075. Found: C, 44.61%; H, 4.87%; S, 18.06%; mol. WL, 1006.

The molecular weight, determined by the vapor pressure method, indicated that the product existed largely in dimer form rather than as the monomer. The infrared spectrum of sulfurized oxymolybdenum di-(p-tertiarybutylphenyl)phosphorodithioate showed the following absorption maxima:

Absorption: Microns Strong 3.45 Moderate to strong 6.83 Moderate 7.27 Moderate 8.4 Strong 8.63 Moderate to strong 10.27 Strong 10.60 Strong 10.90 Moderate 11.85 Strong 12.02 Moderate 12.72 Weak to moderate 14.90

Example V In the preparation of sulfurized oxymolybdenum di- (nonylphenyl)phosphorodithioate, pure molybdic oxide, 72 grams (0.5 mole), was placed in 500 ml. water and dissolved by 35 grams of 50% sodium hydroxide solution (0.44 mole) according to the method described in Example IV. Sulfuric acid, 21.7 grams of 96% acid (0.21 mole), was added and the solution was cooled below 50 C. before adding 534 grams of di-(nonylphenyl)phosphorodithioic acid (1.0 mole). The resulting mixture was heated for two hours at 100 C. and then cooled. A brown oily layer was separated and washed first with water and then with methanol. The oil was dissolved in hexane and filtered, and the solvent was evaporated to yield 521 grams of crude brown, liquid sulfurized oxymolybdenum di- (nonylphenyl phosphorodithioate.

Sulfurized oxymolybdenum di-n-propyl and di-n-amylphosphorodithioates were prepared similarly.

Example VI Several sulfurized oxymolybdenum organophosphorodithioates were prepared in the same manner as described in the previous examples except that the organo group ethylhexyl) derivative is a good extreme pressure agent in lubricating grease.

Example VIII was a f r i e i gg S 0 g 3; g gig; 12 1 5 Timken tests in oil were also performed with sulfurized cosity index, high aromatic content oil, copper and iron oxymolybdenum-dl (2'ethy1heXy1)P hosphorodlihloate of wire oxidation catalysts and 5% by weight of a diiferent Exemp eddmg 2% to basefd on thegelght e sulfurized oxymolybdenum organophosphorodithioate in .poeitlon i portborlle SA f 9 mmera' 250 ml. beakers and placing the beakers inacirculating air 10 u neautmg e1 evmg a Say 0t f e 87 oven at 250 F. The beakers were checked daily for F 210 and 1030 l f at and a 9 sludge formation and evolution of hydrogen sulfide and Index of A eempeeltlen eentelemg no eulfunzed the time of breakdown was noted as indicated in Table I Oxymelybdenum organophosphorodlthloate served as hsrebelow. treated control.

TABLE I These compositions were subjected to the Timken Load organo group; Additive life (days) Bearing Test as described in Example VII but modified p 1 by flooding the rotating ring and the block it presses 1So propy1 1 against with the test lubricant, which is. maintained at lsogbutyl 3 100 F., and beginning with a -pound load.

1 1 20 The OK. or passing loads in the lubricating oil are 2 h 1 1 3 indicated in Table III.

Nonylphenyl a 21 III f Ran 14 days at 250 F., then 7 days at 300 13:. After ter- TABLE min-ation at 21 days, the oil was still in fair condition. 25 Organo r This example demonstrates that the compounds of the 2-ethylhexyl, percent: O.K. load (lbs.) invention have acceptable heat stability and that the heat 2 20 stability of sulfurized oxymolybdenum di(nonylphenyl) 4 70 phosphorodithioates was especially outstanding. Control 7 This example also demonstrates that sulfurized oxy- Example VII molybdenum d1-.(2-ethylhexyl)phosphorodithloate is an Tlmken tests in lubricatlng grease Wfire perfomed Wlth excellent pressure agent when present in sufiiciently high several compounds of Examples 1, III and V. eparate concentration portions of a lithium 12-hydr0xystearate grease containing E 1 IX no additive other than this thickening agent were com- Xamp e bined with each sulfuriged oxymolybdenum organopho Four-Ball tests in oil were performed with the base Phorodithioate in varying Propomons; Sulfurized oil described in Example VIII containing 2%, based on molybdenum diisopropylphosphorodithioate was tested at the Weight of the composition of sulfurized oxymolyb 2% based on the of the composite)? and Sulfunzed denum organophosphorodithioates. These compositions gggg ggfitfif f f fg gfjg g; igg g i l gg g 40 and a control were tested in the Shell Four-Ball Lubricant 5 1 1 S 0 Tester, in which a 0.5-inch steel ball was rotated in concontilol without an organophosphorodithioate was also tact with three Similar bans which were clamped in a tes ieh crease Compositions were Subjected to the Timken stationagy position to provide the rotating ball with three t Endurance Test which is a recognized test of antiwear F 5 gsgg g a 10a d of 40 kg was applied to the properties in the Timken Lubricant Tester in which a 49 ball rotating at 6 rpm for hour The average tgfggg g sr a ii j gg gg iifi g z fig gsg diameters of the wear scars on the three stationary balls steel block was pressed against it by a system of weights meesgred and were reported In fi h and levers. A ten-pound weight was used and the test or Xtreme. Test (We est.) usmg t e was run for a maximum of eight hours or until seizure 50 Seine equipment Increasing loads were apphed for 9 occurred. The time to failure was recorded in hours. mmute ee'eh to the retatmg i the lead at Whleh These grease compositions were also subjected to the erg li l f 221 81 diteminegd F d 1T Timken Load Bearing Test by varying the weights used, st g g 5 esen e e era beginning with a 20 pound load and raising it by l0-pound an er et 0 an aeeepte measure 0 increments, to determine the highest weight which did not extreme pressure and 'antlwear propereles used the Same produce scoring of the block in ten minutes of running equlpmegt' A f of loads was apphed for ten Seconds time This Weight was recorded as the passing or each until welding occurred. The wear scars on the balls 10 ad, a wen known measure of the load carrying capacity were measured and the mean load at weld was calculated of a lubricant from the size of the scars.

The results'of these tests are Shown in Table IL The results of these tests are listed in Table IV here- TABLE 11 below TABLE Iv Endurance test E Scar Width 0 K- l Wear Test 1 1 333: Mean Hertz Organo Group Hours Organo Group (111111.) Test (kg) Load (kg.)

12 8 1-0 2- th 1h 1; i ifilixy'fi e 2%.? 0. 51 190 35 2% 2 s. s 1. i, 1. 1 20 4% 205 44 4%1111111 s 1.1 so Nonylphenyl- Nonylphenyl: 2% 0. 67 155 22 8.8 1.1 70 4% 170 35 1[6(8) 164E): .5 Cont1'0l 105 18 1 Welds in 10 sec.

Dlittt. s d. S'd. lvelyhght sconne 2 up ca e es s cm me It is evident from Table IV that the sulfurized It is evident from this example that the compounds oxymolybdenum organophosphorodithioates as additives of the invention are antiwear agents and the di-(2- exhibit good extreme pressure and antiwear properties.

7 Example X TABLE V Extreme pressure Mean Hertz Organo Group test (kg) load (kg) i-Propyl 2% 265 i-B utyl 2% 230 2-ethy1hexyl:

2% 195 29 4% 235 p-Tertiary-hutylphenyl 2%. 290 Nonylphenyl:

a 175 29 4% 215 Control 115 18 The results of the above test also show that the sulfurized oxymolybdenum organophosphorodithioates as additives exhibit excellent extreme pressure and antiwear properties.

Example XI The Norma-Hofiman Test, ASTM D-942, in which twenty grams of grease distributed between five glass dishes is heated at 210 F. in a bomb filled with oxygen initially at a pressure of 110 p.s.i.g., was carried out with certain grease compositions of Example VII. The pressure was read daily and loss of pressure was recorded at the end of 100 hours and 500 hours.

Table VI indicates the results of this test.

TABLE VI Pressure loss (lbs.)

Organo Group 100 hrs. 500 hrs.

2-ethylhexylz 2% 4 18 4% 7 22 Nonyl henyl:

3 17 4 4 23 Control 32 1 50 1 Reached a 50 lb. pressure drop at 300 hrs. and for the control the test was terminated.

This example demonstrates that the compounds of the invention act as antioxidants in grease.

Having set forth the general nature and specific embodiments of the present invention, the true scope is now particularly pointed out in the appended claims.

What is claimed is:

1. A composition comprising (A) a lubricating oil or grease and (B) as an additive with antiwear and extreme pressure properties a compound having the generic structure:

wherein R is an alkyl, cycloalkyl, aryl or alkaryl having 1 to 30 carbon atoms.

2. The composition according the amount of additive is from 0.2% to 20%.

3. The composition according to claim 1 in which (A) is a lubricating oil and in which R in the additive compound is an alkyl.

4. The composition according to claim 1 in which (A) is a grease and in which R in the additive compound is an alkyl.

5. The composition according to claim 1 in which (A) is mineral lubricating oil and in which R in the additive compound is Z-ethylhexyl.

6. The composition according to claim 1 in which (A) is mineral lubricating oil and in which R in the additive compound is nonylphenyl.

7. The composition according to claim 1 in which (A) is a grease containing an alkali metal soap and in which R in the additive compound is p-tertiary-butylphenyl.

8. The composition according to claim 1 in which (A) is a grease containing an alkali metal soap and in which R in the additive compound is isopropyl.

9. A method for forming a composition having antiwear and extreme pressure properties which comprises reacting a neutralized molybdate solution with an organophosphorodithioic acid at a temperature of about to C. for about 1 to 5 hours using about 2 mols of phosphorodithioic acid reactant for each mol of the molybdate reactant to provide a reaction product having the generic structure:

wherein R is an alkyl, cycloalkyl, aryl or alkaryl having 1 to 30 carbon atoms; and adding a minor amount of said reaction product to a lubricating oil or grease.

to claim 1 in which References Cited UNITED STATES PATENTS 3,356,702 12/1967 Farmer et al. 260-429 3,400,140 9/1968 Rowan et al. 25232.7

DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner U.S. Cl. X.R. 252-41, 400

CERTIFICATE OF CORRECTION Patent No. Dated February 97 Inventor(3) Eugene V. Rowan and Homer H. Farmer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

COLUMN 1 line 1 "sulforized" should be --sulfurized--; COLUMN 1, line 5 delete "the"; COLUMN 2, line 1, "mole" should be --mols--;

COLUMN line "exymolybdenum" should be --oxymolybdenum--; COLUMN line E i, '.'di-isobutylphosphereditioate" sheuld be COLUMN 4, lin 33,

-.-- di-isobutylpho sphoredithieat e-- SIGNED AND SEALED JUL 1 4 1970 ii AM Edwin] H. Fletcher, Ir. WHILIAM E. m. E Officer wmissimlel Patents 

